Turbidimeter



1960 c. G. WIPPLER 2,964,640

TURBIDIMETER Filed April 24, 1958 IN VEN TOR.

CONSTANT GEORGES WIPPLER flm Md 0% ATTO EYS TURBIDIMETER Constant Georges Wippler, Epinay-sur-Orge, France, assignor to Compagnie de Saint-Gobain, Paris, France Filed Apr. 24, 1958, Ser. No. 730,561

Claims priority, application France May 31, 1957 11 Claims. (Cl. 250-218) This invention relates to a turbidimeter, for determinof various fluid ing the degree of turbidity or the opacity media such as liquids and gases.

novel improved turbidimeter.

electric type.

Still another object of the invention is the provision of a turbidimeter which is compact, rugged, simple in construction, easy to install, and easy to clean.

Yet another object of the invention is the of a novel method of turbidimetry. i

assists Patented Dec l3,

.- the turbidity measurements may be made in the environf ment of the medium to be observed, as in confined laboratory containers or receptacles. v

In accordance with the invention, the light rays from a light source pass once through the medium to be observed, are reflected by a mirror, and again pass through the medium before they are intercepted and/detected. Because the light rays'traverse the medium twice before they areintercepted and detected, the effect of the turbidity of the medium upon the means for detecting the light rays is doubled. This increases the sensitivity of;

the apparatus considerably. b

.The apparatus of theinvention is preferably made as acompact portable unit having one end provided with a medium-receiving chamber. The t-urbidimeter need merely be introduced intothemedium to be observed so thatsuch. medium flows into the chamber. Thus no special niedium -receiving'tanks or containers are necessary and a process being observed need not be disturbed.

Turning now to the illustrative embodiment of turbidimetershown in the drawing, such apparatus has a holprovision I The above and further objects and novel features or" the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. a

to like parts throughout the'several' views,-

'Fig. 1 is a fragmentary view in side'ele'vation oft-l ie lower, material-receiving end'of an illustrative-embed"? ment of turbidimeter made in accordance w'ith'the-Ti vention, the medium-admitting apertures in the'lo'wen instrument being shown par- '5 end of the housing of the tially closed; and

Fig. 2 1s a view taken generallyin vertical-"axial-se ction through the illustrativeturbidimeter; the mediuin-" admitting apertures being shown in fully'opened 'position.

Prior turbidimeters generally comprise a'- source '0 light and a photoelectric cell between which there is positioned a transparent tank or container containing the' medium to be observed. Such 'prio'r turbidimeters are' relatively cumbersome, and require the introduction of the medium into the tank, which is often inconvenient.

This is especially true when it is desirable to be able to follow changes in turbidity in a medium in a container in production apparatus, for example, in the continuous pretents, agitators, means for adding reagents, etc.-

The turbidimeter of the invention overcomes the above outlined difiiculties attendant upon prior turbidime'ters,

- n the drawings, wherein like reference-characters refer i hivsubrst-anfiany Sealed together. I

lowtubular body 1, .made for exampleof metal. .A lens 2.is located. intermediate the length of body 1,- and is. held: centrally therein. The upper end of body' .1 is.

A closed by atubular-casing 3 supporting an electric light 1' bulb 4 the filament 5 of which provides a source of visible light. To the lower end of. body 1 there is fixedlyse- Y cured a headd containing a photoelectric cell 7, 7a. Such cell is held in place by a coil compression spring 8-1 and an internal insert ring member 9. As shown, the 1 *"rim of 'the photo-electric cell 7, 7a rests upon an in-.-

ternalshoulder in head 6, andspring 8 acts between the lower end of-ring 9. 'Head 6 may be secured to the lower end of body 1 as by a threaded connection between them. Preferably such parts are connected so as to be .Thephotqelectric. 6,611.7, 7a hasialig'ht impervious diaphragmftnember, 7', and, a layer ,7a of photosensitive, material on,thef.lower. face of the diaphragm 7. The diaphra'gmlis .providedjwith a central aperture 10, The

. igl ow'er of lensz' and the position of photoelectric cell'l'l,

7ti lare such that the image of thesource 5 is located in the plane of'ph'otosensitive layer 7a of the photoelectric cell. Below .the photoelectric cell the head 6 is sealed by a transparentinipermeable member such as a plate or block and permits themaking of turbidity measurements-which fare rapid and accurate.

Such measurements may be made intermittently or continuously, in gaseous or liquid media, and the apparatus of the invention is suchthat through. aperture 10 in diaphragm 7 and impinging upon the mirror are reflected by the mirror as a beamof 'su otfglass. In the illustrative apparatus such member is a cylindrical, glass member, 11. .A seal between member 11 and the head 6 is effected by an annular packing member lzlwhich is mounted in a 'seat in head 6 and held under compression against member 11 by a retainer ring 13 threaded into the lower end of head 6. .The. apparatushas ,a cylindrical extension 14 at its" lower end. 'Member 14 is attached to head 6 as by the illustrative threaded connection between them. At its lower end. member 14 carries a transversely disposed" concave mirror 15;the concave reflective face of which; is directed toward the photoelectric cell. The curvature of mirror..15 is ,such that.the light rays, upo'n p'assing" stantiallypa'rallel rays. I

The member '4 has a, plurality of apertures such 1'6'a, 16h, 16c, 'etc. throug h its sidewall; pre'fer'abl shown, 'such ap'erturesarein' the "form of restartnaw windows. The windows allow the medium beingserved to -flow into the observation chamber formed by member 14 below grass block l'l and abovemirm'r 15.

Since the apertures allow external light to pass therethrough, there is the danger of decreasing the sensitivity of the apparatus in making turbidity measurements. To overcome this, the apparatus is so designed as to diminish as much as possible the passage of external light into the chamber. In the illustrative apparatus the windows in member 14 which are near the photoelectric cell are narrower thanthose which are at the seam of th apparams and thus further from such "cell. v

Further, the apparatus is provided with means to as: just the area of the win ows throughthe wall of the observation chamber. Such means are tip-of a tube 17 which-has apertures in the wall thereof whichare the same or substantially the same as those in member 14. Tube 17 is telescope'd within member 14 and has frictional engagementtherewith. 7 When tube 17 is displaced relative to member 14, as for example longitudinally as shown in Fig. l, the operator can easily mask more or less of the aperture area, as desired, depending upon the external light level and the opacity or turbidity of'the medium being observed. It will be understood that tube 17 may alternatively be displaced angularly relative to member 14, or both angularly and longitudinally, to

achieve the desired cutting downof the amount of ex-' ternal light reaching the interior of the observation chamber.

The apparatus functions as follows: I

The member 14 is immersed inthe medium being ob' served, so, that the observation chamber in such member is filled with the medium. Light emittedbylightsourcepasses throughaperture in thephotoelectric cell 7, 7a, through glass block 11, and through the medium in the observation chamber to mirror 15. The incident light is reflected by mirror 15 in the form Ora beam of parallel light rays, such beam passing through the inedium in the observation 'chamber,'through glass block 11, and is cell illuminated by a second light source identical with.

the first light source, there being avariable' opacity compensator system interposed between the secondlight source and the second photoelectric cell. Suchcompensator system may be, for'example, an apuen wedge adjusted by micrometer means. The 'ou'tput'circuits of the two photoelectric cells are connected through a galvanometer or the like so that the currents'from the'two thus lower end thereof, a generally transverse mirror supported currents may be compared, andby'suitable adjustment of the'optical compensator for thesecond cell, may be made equal. I

The turbidity of a medium being observed may'thus be measured. When such turbidity varies, its changes may be followed in a continuous manner by constantly reestablishing the equality [of the opposing currentsjjof the two cells, by the lineardispl'acement of'the optical compensator for the'se'condi cell. r r.

The apparatus of the invention may be" employedjto advantage in observing the'pre'cipitation or a high ay me! frern solution. The member 1401? theapparatus is immersed in the solution, the. precipitating i bit by: bit, a tdjthe. resulting turbidity of. observed by use; r.. e appsmtsa of 1 the 'inv manner abovje described.

The current emitted Although only one embodiment of the invention has been illustrated in the accompanying drawings and described in the foregoing specification, it is to be expressly understood that various changes, such as in the relative dimension of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention may be made therein with-out departing from the spirit and scope of the invention as will now be apparent to those skilled in the art.

What is claimed is:

1. A turbidimeter comprising a mirror adapted to be positioned in a medium to be observed, means to direct an incident beam of luminous rays through a portion of the medium onto the mirror along a path coaxial of the mirror, the mirror reflecting the incident beam .to produce the reflected beam coaxial of the incident beam, and means to intercept and detect the rays reflected by the mirror after they have passed through a portion of the medium. I V w h e 2. A turbidimeter as defined in claim 1, comprising a source of light, and a supporting frame mounting the source of light, the mirror, and the means to intercept and detect the reflected rays so that they are parts of a unitary structure.

3. A turbidimeter as defined in claim 2, wherein the supporting frame is an outer tube, the source of light is disposed in the upper end of the tube, the mirror is supported on the lower end of the tube, the means to intercept and detect the reflected rays is located intermediate the ends of the tube,-and comprising means to admit-themedium to be observed into a chamber in the tube above the mirror. 7 V t I 4. A turbidimeteras defined in claim 3, wherein the means to intercept and detect the reflectedrays comprises a photoelectric cellsupported in the tube below the light source and protected from the direct rays from the light source. V V V e 5. A'turbidimeter as defined in claim 4, comprising means to seal the photoelectric cell against the admission thereto of the medium being observed in the chamber in the lower end of the tube. I

6. A turbidimeter as defined in claim 3, wherein the means to admit the medium to the said chamber comprises openings through the wall of the tube whereby the medium may flow into the chamber, I

7. A turbidimeter as defined in claim 6, wherein the openings in the wall of the tube are in the form of a.

series of axially spaced rectangular windows, the windows nearer the means to intercept and detect the reflected rays being spaced closertogether than the windows adiacent the lower end of the tube. I I

8. A turbidimeter as defined in claim 6, comprising means whereby the amount of external light passing through said openings may be diminished. 9. A turbidimeter as defined in claim 8, comprising an inner'tube telescoped within the outer tube at thelower endof the latter, the inner tube having a series of axially spaced windows generally, similar to the windowsin the outer tube, the two tubes being relatively displaceable to vary the effective size of the aperturescommunicating with;the:charnber. t t p 10. A turbidimeter comprising a tube, a source of. light inthe upper part of the tubedirecting anincident beam A the diaphragm and around the opening therein so as to be shielded from the direct rays from the light source, a chamber in the lower end of the tube above the mirror for receiving a medium to be observed, means to admit said medium to the chamber, and transparent means below the photoelectric cell forming the upper end of the chamber and sealing the cell from said medium.

1 1. A turbidimeter as defined in claim 10, wherein said transparent means is a piece of glass in contact with the layer of photosensitive material.

References Cited in the file of this patent UNITED STATES PATENTS Freygang Oct. 27, 1931 Frommer July 31, 1951 Albert Jan. 1, 1952 Miller Mar. 23, 1954 Canada June 30, 1959 FOREIGN PATENTS Great Britain Feb. 9, 1938 France Mar. 8, 1950 

